Abstract This review covers literature data summarizing, on one hand, the chemistry of essential oils and, on the other hand, their most important activities. Essential oils, which are complex mixtures of volatile compounds particularly abundant in aromatic plants, are mainly composed of terpenes biogenerated by the mevalonate pathway. These volatile molecules include monoterpenes hydrocarbon and oxygenated monoterpens, and also sesquiterpenes hydrocarbon and oxygenated sesquiterpens. Furthermore, they contain phenolic compounds, which are derived via the shikimate pathway. Thanks to their chemical composition, essential oils possess numerous biological activities antioxidant, anti-inflammatory, antimicrobial, etc… of great interest in food and cosmetic industries, as well as in the human health field. View Full-Text